Recently, the U.S. Court of Appeals for the Third Circuit set the appeal in United States v. Mitchell for oral argument before the entire 14-judge court. In Mitchell, the district judge had refused to permit the government to collect DNA from a man who had been arrested and who faced trial for felony drug charges. The judge held that sampling and studying a person's DNA represents an intrusive search that, in the absence of an actual conviction, cannot be justified without probable cause and a warrant.

Though a three-judge panel of the Third Circuit heard oral argument in the case, the appeals court departed from ordinary practice and failed to release a decision from the three-judge panel prior to scheduling the case for rehearing en banc (that is, before a full bench).

The issue of routinely sampling the DNA of people who have not been tried and convicted of an offense is an important one that will likely make its way to the U.S. Supreme Court.

Federal Law and DNA Collection

The DNA Analysis Backlog Elimination Act of 2000 ("the 2000 DNA law") initially required the collection of DNA samples from people who had been convicted or were on probation, parole, or supervised release for a qualifying federal offense. Once the DNA sample was collected, the Director of the FBI would receive the sample for analysis and inclusion in the Combined DNA Index System ("CODIS"), a national DNA database. As its title reveals, one important purpose of the 2000 DNA law was to help identify the perpetrators of unsolved crimes.

Most of the U.S. Courts of Appeals have had occasion to consider challenges to the Fourth Amendment validity of the 2000 DNA law, and each one has upheld it against such challenges.

In 2006, however, Congress amended the 2000 DNA law to extend to the collection of samples from people who have been arrested or face charges. In January of 2009, this expansion went into effect, when the Attorney General promulgated regulations requiring agencies that arrest, detain, or supervise individuals facing charges to collect DNA samples from these individuals.

Thus, the DNA law now applies not only to convicts but to pre-trial detainees as well. It is this expansion that Ruben Mitchell successfully challenged in the trial court in Mitchell and that awaits review by the full 14-judge panel of the Third Circuit.

The Fourth Amendment, and the Question of When a Search Is Reasonable

To find that DNA collection violates the Fourth Amendment rights of an arrestee, the court must determine, first, that collecting and analyzing DNA is a "search" for purposes of the Fourth Amendment; and, second, that such a search of an arrestee is "unreasonable."

Under U.S. Supreme Court precedents, the Fourth Amendment applies to only "searches and seizures." If collecting and analyzing DNA do not constitute a search or seizure, then they do not trigger the protection of the Fourth Amendment. Because Mitchell claims an invasion of his privacy, the relevant question is whether DNA sampling constitutes a "search," which the Court has defined as the invasion of a "reasonable expectation of privacy." If and only if people have a legitimate claim to privacy in their DNA does DNA sampling constitute a "search" under the Fourth Amendment.

In another reported decision on this issue, Judge David S. Cercone of the U.S. District Court for the Western District of Pennsylvania determined that DNA testing does qualify as an invasion of a reasonable expectation of privacy, i.e., a search. He wisely broke down the question into two separate parts: First, does the taking of the sample itself -- by a blood test or by a buccal (inside-of-the-cheek) swab -- invade a suspect's reasonable expectation of privacy? Second, does the subsequent chemical analysis of the DNA sample for physiological information invade such a reasonable expectation? Judge Cercone answered both questions in the affirmative, and thus held that freedom from DNA sampling and analysis falls within the Fourth Amendment's protections.

Does DNA Sampling Count As a Search in the First Place?

Before reaching the question of whether this sort of a search is reasonable, it is worth pausing to consider briefly the argument that DNA sampling is not a search at all. As I described in an earlier column, the physical intrusion involved in taking a DNA sample by buccal swab is arguably not a significant aspect of DNA sampling, when it comes to important Fourth Amendment questions. Though the intrusion of taking the sample corresponds neatly with the sort of intrusion involved in other searches -- by invading the person's physical privacy -- it is becoming increasingly unnecessary to DNA collection, and it is also likely to be the less objectionable feature of the invasion to suspects who raise Fourth Amendment objections.

It is increasingly feasible to take DNA samples from a suspect in custody without actually having to touch him at all -- by collecting biological material that the suspect sheds (when he drinks and disposes of a can of soda, or when he brushes his hair, for example). And regardless of how the government obtains his DNA, the suspect's main concern will likely be with the resulting revelation of potentially-countless physiological facts about him, rather than with the removal of cheek cells by a medical worker. In addition, of course, DNA profiling would allow the police to keep track of the person's whereabouts -- even when there is no crime scene at issue.

If I am right, then the heart of the alleged invasion of privacy in DNA collection -- the analysis of physiological data about the person, and the ability to keep track of his comings and goings -- may fall victim to existing Supreme Court cases holding that analyzing the information contained in discarded or shared material (such as garbage left at the curb) does not invade any reasonable expectation of privacy. Stated differently, once a person has parted with something voluntarily, it may be the case that he retains no residual privacy in the information that can be unearthed as a result.

Judge Cercone, however, accepted an alternate vision of the Fourth Amendment as protecting informational privacy of this sort and found that the chemical analysis of DNA "is also a search covered by the Fourth Amendment," separate from the search that occurs upon extraction of the sample.

As I discussed in greater detail in my earlier column, I believe this position, though controversial, is defensible under precedents that include Ferguson v. City of Charleston. There, the Supreme Court determined that when a suspect has consented to urinalysis by the medical provider who helped her to give birth, and the police subsequently analyze the urine for the presence of cocaine, the police have triggered the suspect's Fourth Amendment rights.

The Fourth Amendment does not, of course, prohibit all searches, but only unreasonable ones. As a general matter, the government may perform a search only on the basis of a warrant that is supported by probable cause to believe that the search will turn up evidence of crime. In other words, the rule is that searches require individualized suspicion. There are, however, exceptions to the rule, and under these exceptions, government officials may lawfully perform searches in the absence of individualized suspicion.

The question, for DNA sampling, is therefore whether it is reasonable to perform this sort of search in the absence of individualized suspicion on people who have been arrested -- but not tried or convicted -- for qualifying offenses under the DNA law.

The Question of Reasonableness

One way to justify the routine taking of DNA from arrestees is to note that people in this category must already submit to routine fingerprinting, regardless of whether there is any reason to suspect that their fingerprints would provide evidence of a crime. One could argue that because DNA samples are used to identify people present at crime scenes -- and not to figure out personal facts about the person from whom the sample is taken, or to track his movements -- the information taken from the sample is really no different from a fingerprint and should be treated the same way, as a Fourth Amendment matter.

People experiencing pre-trial detention also have a diminished expectation of privacy, relative to people who have not been arrested for anything. The Supreme Court has, for example, in Bell v. Wolfish, upheld body-cavity searches of inmates after contact visits with people from outside the institution, as well as routine room (cell) searches during which inmates must remain outside their rooms -- both, in the absence of any individualized suspicion.

With respect to fingerprinting, Judge Cercone rejected the analogy between DNA and fingerprints as "pure folly," citing the "complex, comprehensive, inherently private information contained in a DNA sample . . . . [including] over four thousand types of genetic conditions and diseases." Judge Cercone was accordingly unwilling to trust the government to limit its analysis of a suspect's DNA to use for identification purposes.

And insofar as the arrestee has a diminished expectation of privacy, Judge Cercone explained, this diminution reflects the special needs that accompany an institutional setting. Searches in jail help ensure security and order by locating weapons and contraband before they can be used and distributed. There is nothing about a person's presence in pre-trial detention (or in a person's simple status as an arrestee), however, that would make the collection of DNA part of the safe and secure running of an institution.

As Judge Cercone explains, the purpose of collecting DNA is to help solve crimes -- an ordinary law enforcement objective that therefore calls for ordinary criminal-procedure protections, including probable cause and a warrant. It is not, in other words, the fact that a person in pre-trial detention is suspected of a crime that justifies body-cavity searches and room searches in which he must remain outside the room. It is, instead, the peculiar and special needs of institutionalized confinement. Accordingly, when such needs are not at issue -- which they are not in any way that would call for routine DNA collection -- the usual Fourth Amendment requirements ought to apply.

Does the Presumption of Innocence Justify Different Fourth-Amendment Treatment for Pre-Trial Detainees?

Judge Cercone suggests that one important fact that distinguishes a pre-trial detainee -- whom he regards as holding the right not to have DNA routinely taken -- and the convict, who does not hold this right, is the presumption of innocence. The judge calls this "the moral polestar of our criminal justice system." Prior to being convicted of a crime, in other words, a person must be treated as innocent. And there is no reason to keep the DNA of an innocent person in a national database of criminals' DNA.

But is the presumption of innocence relevant to the issue of whether the government may routinely sample and analyze pre-trial detainees' DNA?

On one hand, it is true that arrestees do not relinquish all of their constitutional rights as they await trial in jail. The reason that their body cavities and rooms may be searched without suspicion has to do with the needs of the institution, rather than the arrestee's status as a person charged with a crime.

On the other hand, a person charged with a crime may be held in jail. That is, such a person -- for a period of time -- loses the fundamental right to freedom from incarceration. That is the reason, after all, that he finds himself subject to random privacy invasions that serve institutional needs in the first place. And the reason that he may be held in jail is precisely because we take seriously the possibility that he truly is guilty of a crime and that he may therefore ultimately be subject to imprisonment or the death penalty -- potential outcomes that could motivate him to flee the jurisdiction and avoid his trial altogether. It would accordingly be inaccurate to say that we treat accused criminals as the equals of other people who have not been accused of a crime.

The presumption of innocence, moreover, as I have elsewhere explained, is not a requirement that people outside a criminal jury must either believe or act as though the accused is factually innocent of any crime. Neither is it an all-purpose rule that prior to conviction, an accused enjoys the same legal status as a person who has not been charged with a crime. It is, instead, a constitutionally-compelled evidentiary rule that requires the prosecution to prove guilt beyond a reasonable doubt as a prerequisite to a jury (or judge) finding a defendant guilty of an offense with which he is charged.

The fact that as part of routine booking -- and in the absence of any fingerprint-relevant suspicion -- a suspect's fingerprints may be taken is just one example of how differently an arrestee may be treated from his peers, simply by virtue of being lawfully under arrest.

In addition, the Supreme Court has previously held that the Fourth Amendment right against unreasonable searches does not turn in any way on the innocence or guilt of a search target. If there is probable cause to believe that evidence will be found on an innocent third party, then, under Zurcher v. Stanford Daily, police may obtain a warrant to search that innocent person.

By the same logic, the fact that a pre-trial detainee is presumed innocent for trial purposes (and may well in fact be innocent) does not invalidate a policy by which all arrestees must provide DNA in order to help identify criminals from a pool of individuals who might, by virtue of having been arrested upon probable cause, have at least an elevated likelihood of criminality.

Is DNA Different?

What makes this case special may ultimately have less to do with the presumption of innocence than with the treasure trove of information that is contained in a small sample of DNA. Unlike ordinary searches, in which the main intrusion occurs at the time of initial surveillance, a DNA sampling -- as Judge Cercone correctly observes -- has the potential to make large quantities of personal information about someone available to the government long after the sampling takes place.

In this sense, DNA squarely raises the issue of informational privacy, rather than spatial privacy, precisely because the physical taking of DNA is not very different from the physical taking of fingerprints (and may indeed be, or shortly become, an entirely nonintrusive collection of discarded biological material).

When the U.S. Court of Appeals for the Third Circuit decides this case, it will accordingly have the opportunity to consider the relatively undeveloped and critical issue of whether, sometimes, the mining of information from materials already in the government's possession might constitute the invasion of a reasonable expectation of privacy.

Sherry F. Colb, a FindLaw columnist, is Professor of Law and Charles Evans Hughes Scholar at Cornell Law School. Her book, When Sex Counts: Making Babies and Making Law, is available on Amazon.